Conference Abstract – GHGT-18: Aerosol and volatile amine emissions in CO2 Amine-based Absorption: A comparison of MEA and CESAR1

Abstract

Chemical absorption using aqueous amine solutions is a well-established method to capture CO2 from industrial gases. The technology has a high level of maturity and is industrially deployed. However, for CO2 capture from exhaust gases, solvent emissions may pose a significant challenge to its widespread adoption. Large-scale implementation requires strict emissions control, ensuring that the release of amines remains below national and international limits. Amine emissions can be gas-phase emissions, resulting from the inherent volatility of the solvents, and aerosol-based emissions, resulting mainly from heterogeneous nucleation and particle growth in the absorber and wash-columns [1]. Such particles grow along the absorber and water wash columns because water, amine, and CO2 are transferred from the liquid and gas phases to the aerosol phase.

Aerosol emissions can be effectively mitigated using demisters in combination with water wash and dry bed sections [2]. However, the efficiency of these mitigation technologies depends on the aerosol inlet size distribution and their growth along the absorber and wash sections. The absorption plant operation and the solvent properties will also impact the absorbent emissions into the atmosphere. While volatile emissions can be easily correlated to the solvent vapor pressure and its liquid activity, aerosol emissions exhibit a more complex and less direct dependence. CO2 absorption kinetics, transport properties, and the equilibrium properties will all impact the final emissions via the aerosol phase.

This work aims to quantify and compare how solvent-specific thermodynamic, kinetic, and transport properties influence volatile and aerosol-based emissions under varying inlet aerosol size and number distributions. The work examines the significance of solvent properties in a broader context, including aerosol emissions, rather than focusing solely on the volatility of the solvent as is usually performed.

Two solvents are used for the study: an aqueous solution of 30 wt.% ethanolamine (MEA) and a blend of 27 wt.% 2-amino-2-methyl-1-propanol (AMP) and 13 wt.% piperazine (PZ), also known as CESAR1. The two systems differ in terms of solvent properties, with one important distinction being that CESAR1 is a blend of two amines [3-6].

Keywords: CO2 absorption; Process Amine Emissions; Amine-based CO2 absorption; MEA; CESAR1

Authors: Diego Morlando, Hallvard F. Svendsen, Hanna K. Knuutila (Department of Chemical Engineering, NTNU)